The iMac s a G5 iSight -- I guess it's supposed to be fine w/out a firmware update (OS etc. are all up to date). I figure it's either incipient power supply failure (boo), a bad peripheral (unlikely as we've not added any recently) or a software issue (random corrupted pref., etc.) If the latter, we trash relevant prefs, reset SMU. reset PRAM, and cross fingers --- that's where we are right now, after getting a solid back up system in place just in case. If asakiyume ends up in the basement again it's probably the power supply, and we've taken the machine in to the local (I hope we have one) AASP (not to be confused with AARP). I'm sticking with fingers crossed, for now.

on the support page, they say that all intel-based macs need a firmware update to solve the random shutdown problem. our macbook had it too until i updated the firmware. it's been fine (knock on wood) ever since i did it.

So, turns out this evil Mac doesn't have the Intel chip. Seems like it must be the same problem, but it's not "documented" for this (version of) this machine. So I guess we just have to watch it die (sigh). Anyway, we reported the problem, so they can add us to their collection of statistics. Meanwhile, they advise doing what we've done--have an external hard drive to back up to, etc...